Cut-off gear for steam-engines



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NI'IED STATES PATENT OFFICE.

C. P. BUCKINGHAM, OF MOUNT VERNON, OHIO.

CUT-OFF GEAR FOR STEAM-ENGINES.

Specification of Letters Patent No. 25,174, dated August 28, 1859.

To all whom it may concern:

Be it known that I, C. P. BUCKINGHAM, of Mount Vernon, in the county ofKnox and State of Ohio, have invented a new and Improved Cut-Off forSteam-Engines; and I do hereby declare that the following is a full,clear, and exact description of the same, reference being had to theaccompanying drawings, making a part of this specification, in which-Figure l represents a vertical longitudinal section of my invention.Fig. 2 is a horizontal section of the same.

Similar letters of reference in both views indicate corresponding parts.

To enable those skilled in the art to make and use my invention I willproceed to describe its construction and operation.

A represents the top of an ordinary valve chest to which a chamber, B,is secured by screws, a, and this chamber communicates with the interiorof the valve chest by openings, b, which are closed by valves, C.

D represents the steam pipe which communicates with the chamber, B,above the valves, C, so that no steam is admit-ted to the valve chestbefore one of the valves, C, is opened. The stems, E, of the valvesextend through stuiiing boxes, F, in the top of the chamber, B, andtheir upper ends are guided in sockets, c, in the top plate, G, of aframing, H, which is firmly attached to the chamber, B. The centralparts, I, of the stems, E, are square, and secured to those parts bymeans of pivots, c, are the drops, J, the upper ends of which are bentover at right angles so as to form arms, K, which rest on flat springs,d, which are secured to the square parts, I, of the stems, E. In orderto prevent the stems binding as they are lifted up, the drops arearranged so as to form two distinct parts, one on either side of each ofthe stems and these two parts unite in the arms, K.

L is the lifter, which is attached to a rock shaft, c, which has itsbearings in the lower part of the framing, H, and which receives motionby means of a crank, M, which connects with a separate eccentric on themain shaft of the engine. The ends of the lifter, L, are forked so thatit acts on both parts of each of the drops, J, at one and the same time,and the springs, CZ, are so adjusted that by their action the lower endsof the drops are brought in such a position, that they can be reached bythe forked ends of the lifter. Vhen the stems, E, are raised by theaction of the lifter, L, the arms, K, which extend near to the center ofthe framing, H, strike against the tripper, N, which is adjustable inthe top plate, G, of the framing, H, so that the arms, K, strike thesame sooner or later.

The operation is as followsr-The eccentric which gives motion to thecrank, M, is so arranged on the main shaft that it is on its extremepoint of motion just as the slide valve in the chest below has closedthe steam-port, and before the slide valve opens t-he steam-port on theother side, the lifter, L, will have been moved far enough to lift thevalve stem so that steam is admitted into the valve chest before theslide valve opens, and as the eccentric has thus to be placed coincidentwith, or a little in advance of the crank of the engine, the lifter, L,will continue to rise during almost the whole stroke of the piston, orat least until the slide valve closes the steam-port. If, therefore, thedrops, J, are not disengaged from the lifter, steam will be admittedduring the whole of the stroke, and the full force of the steam will begiven to the piston when the slide valve opens either one of thesteam-ports. If the tripper,-N, is depressed, however, the arms, K, willstrike against it sooner or later, and as these arms are depressed, thedrops, J, are disengaged from the lifter, and the valves, C, are closedso that the steam is cut olf sooner or later. It will be noticed that,in order to gain this object, it is necessary to have two valves, C,which communicate with the same valve chest, and which are operated uponalternately by the same eccentric. .The tripper may be attached directlyto the governor, as, after the valve has risen so as to admit steamunder it, the pressure on the lifter will be so light as not to disturbthe motion of the governor balls by the arms, K, striking the tripper.

Vhat I claim as new, and desire to secure by Letters Patent, is

The employment of the tripper N, when constructed and arranged as shownso as to be adjusted and to trip both valves, in combination with dropsJ, arms K, and lifters L, as herein set forth.

C. P. BUCKINGHAM.

Witnesses:

J. W. WHITE, H. P. Ur'roN.

